Image forming apparatus

Abstract

This provides a configuration that can suppress fluctuations in rotational speed in the drive train. [Solution] An image forming apparatus comprising: a first transmission member; a second transmission member; a third transmission member that rotates in a first rotational direction about a rotation axis, engaging with the first transmission member and being separated from the second transmission member; a fourth transmission member that rotates in a first rotational direction about a rotation axis, engaging with the second transmission member and being separated from the first transmission member; a biasing member connected to the third and fourth transmission members, biasing one of the third and fourth transmission members in a first rotational direction and the other in a second rotational direction opposite to the first rotational direction; and a connecting portion connected to the first and second transmission members such that a closed-loop drive train is formed including the first transmission member, the second transmission member, the third transmission member, the biasing member, and the fourth transmission member.

Description

Technical Field

[0001] The present disclosure relates to an image forming apparatus having a mechanism for driving a rotating body in an image forming apparatus such as a copying machine, a printer, a facsimile machine, etc.

Background Art

[0002] It is known that the rotation of a rotating body is accurately maintained by transmitting a driving force to the rotating body through a load body such as a flywheel or a friction wheel (Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When a drive train for transmitting a driving force is formed by engaging a plurality of transmission members and there is backlash at the engaging portion between the transmission members, fluctuations in the rotational speed may occur in the drive train.

[0005] An object of the present disclosure is to provide a configuration capable of suppressing fluctuations in the rotational speed in a drive train.

Means for Solving the Problems

[0006] In order to solve the above problems, the image forming apparatus of the present disclosure is an image forming apparatus, a first transmission member, a second transmission member, a third transmission member that rotates in a first rotation direction around a rotation axis, engages with the first transmission member, and is separated from the second transmission member, A fourth transmission member that rotates in the first rotational direction about the rotation axis, the fourth transmission member engaging with the second transmission member and being separated from the first transmission member, A biasing member connected to the third transmission member and the fourth transmission member, the biasing member biasing one of the third transmission member and the fourth transmission member in a first rotational direction and the other of the other in a second rotational direction opposite to the first rotational direction, A closed-loop drive train is formed including the first transmission member, the second transmission member, the third transmission member, the biasing member, and the fourth transmission member, with a connecting portion connected to the first transmission member and the second transmission member, It has, The rotational speed of the third transmission member is the same as the rotational speed of the fourth transmission member. It is characterized by the following: [Effects of the Invention]

[0007] According to this disclosure, a configuration can be provided that can suppress fluctuations in the rotational speed of the drive train. [Brief explanation of the drawing]

[0008] [Figure 1] Cross-sectional view of an image forming apparatus [Figure 2] Diagram showing the drive train of the first embodiment. [Figure 3] Enlarged view showing the meshing state of the gears in the drive train. [Figure 4] A diagram showing the drive train of the second embodiment. [Figure 5] A schematic diagram showing the drive train of the second embodiment. [Figure 6] A schematic diagram showing the drive train of the second embodiment. [Figure 7] Cross-sectional view of the image forming apparatus of the third embodiment [Figure 8] Diagram showing the drive train of the third embodiment. [Figure 9] Diagram showing the drive train of a modified example. [Figure 10] Diagram showing the drive train of the fourth embodiment. [Figure 11] A diagram showing the operation of the drive train in the fourth embodiment. [Figure 12] Figure showing the drive sequence of the fifth embodiment [Figure 13] Figure showing the operation of the drive sequence when the motor of the fifth embodiment rotates forward [Figure 14] Figure showing the operation of the drive sequence when the motor of the fifth embodiment rotates backward

Best Mode for Carrying Out the Invention

[0009] Hereinafter, with reference to the drawings, the mode for carrying out this invention will be exemplarily and detailedly described based on examples. However, dimensions, materials, shapes, relative arrangements, etc. of the components described in this embodiment should be appropriately changed according to the configuration of the device to which the invention is applied and various conditions. That is, it is not intended to limit the scope of this invention to the following embodiments. Also, although a plurality of features are described in the embodiment, not all of these plurality of features are essential to the invention, and the plurality of features may be arbitrarily combined. Furthermore, in the attached drawings, the same reference numerals are assigned to the same or similar configurations, and duplicate explanations are omitted.

[0010] As the order of explanation, first, using FIG. 1, the overall schematic configuration and the image forming process common to the first embodiment and the second embodiment of the image forming apparatus will be described. Next, using FIG. 2, the drive configuration of the photosensitive drum will be described in detail.

[0011] <Overall Schematic Configuration of the Image Forming Apparatus> FIG. 1 is a cross-sectional view of the image forming apparatus 1. The image forming apparatus 1 is a four-color full-color laser beam printer using an electrophotographic process, and forms a color image on a recording material S. This image forming apparatus 1 has photosensitive drums (2K (black), 2C (cyan), 2M (magenta), 2Y) as image carriers that carry an electrostatic latent image. Since the configurations of the photosensitive drums 2K, 2C, 2M, and 2Y are common, in the following description, the characters YMCK indicating each color may be omitted. The image forming apparatus 1 has a charging member (charging roller) 4 that charges the photosensitive drum 2. Further, the image forming apparatus 1 has a developing unit having a developing member (developing roller) 5 that develops the electrostatic latent image formed on the photosensitive drum 2 and a toner container 6 that stores a developer (toner) supplied to the developing roller 5. The charging roller 4 and the developing unit are provided for each photosensitive drum 2 (2K, 2C, 2M, 2Y). The image forming apparatus 1 includes a cartridge P that is removable from the apparatus main body. In the present embodiment, the cartridge P includes the developing unit, but the cartridge P may further include the photosensitive drum 2 and the charging roller 4.

[0012] Below each cartridge P, a laser scanner 7 is disposed as an exposure device for each photosensitive drum 2 (2K, 2C, 2M, 2Y). Further, below this laser scanner 7, a feeding unit that supplies the recording material S (generally paper) to the image forming unit is disposed. This feeding unit includes a paper feed cassette 9 that loads and stores the recording material S, a paper feed roller 10, and a separating unit 11. Further, the image forming apparatus 1 has a registration roller pair 12.

[0013] Above each photosensitive drum 2, an intermediate transfer unit 13 is disposed. This intermediate transfer unit 13 includes an intermediate transfer belt (hereinafter referred to as a transfer belt) 14 to which the toner image formed on each photosensitive drum 2 is primarily transferred. The transfer belt 14 is supported by a driving roller 15 and a tension roller 16.

[0014] Each photosensitive drum 2 (2K, 2C, 2M, 2Y) is in contact with the underside of the transfer belt 14. The contact area between each photosensitive drum 2 and the transfer belt 14 is the primary transfer area. Inside the transfer belt 14, primary transfer rollers 17 are arranged at positions corresponding to each photosensitive drum 2. The transfer belt 14 is circulated by the drive rollers 15 in the direction of arrow V while in contact with all the photosensitive drums 2. The surface speed of the transfer belt 14 is faster than the surface speed of the photosensitive drums 2. In this embodiment, the surface speed of the transfer belt 14 is greater than 100% and less than 110% of the surface speed of the photosensitive drums 2. Setting the speed of the transfer belt 14 faster than the photosensitive drums 2 increases the toner transfer efficiency and reduces the amount of untransferred toner remaining on the surface of the photosensitive drums 2. A predetermined primary transfer voltage is applied to the primary transfer rollers 17.

[0015] Furthermore, a secondary transfer roller 18 is in contact with the transfer belt 14. The transfer belt 14 is sandwiched between the drive roller 15 and the secondary transfer roller 18. The contact area between the secondary transfer roller 18 and the transfer belt 14 is the secondary transfer area. A predetermined secondary transfer voltage is applied to the secondary transfer roller 18. A cleaning blade 3, which removes toner from the transfer belt 14, is in contact with the transfer belt 14. The secondary transfer roller 18, each primary transfer roller 17, and the tension roller 16 are driven by the transfer belt 14. The torque required to rotate the drive roller 15 is greater than the torque required to rotate each photosensitive drum 2.

[0016] The upper part of the image forming apparatus 1 is equipped with a fixing roller pair 19 and a discharge roller pair 20. The top surface of the image forming apparatus 1 is a discharge tray 21.

[0017] <Image forming process> Next, the image forming process of the image forming apparatus will be explained using Figure 1.

[0018] Each photosensitive drum 2 is driven at a predetermined rotational speed in the direction of the arrow in Figure 1. The charging roller 4 uniformly charges the surface of the rotating photosensitive drum 2. Laser light L corresponding to the image information is emitted from the laser scanner 7 to the photosensitive drum 2. As a result, an electrostatic latent image corresponding to the image information is formed on the surface of the photosensitive drum 2. This electrostatic latent image is developed as a toner image (developer image) by toner (developer) supplied by the developing roller 5.

[0019] The toner image supported on the photosensitive drum 2 is then transferred to the transfer belt 14 in the primary transfer section by the primary transfer roller 17. In this embodiment, any toner remaining on the photosensitive drum 2 that is not transferred to the transfer belt 14 is collected by the developing roller 5. The toner image transferred to the transfer belt 14 is transported to the secondary transfer section as the transfer belt 14 rotates. Meanwhile, the recording material S supplied from the feeding unit is transported to the secondary transfer section by the registration roller pair 12. The toner image transferred to the transfer belt 14 is then transferred to the recording material S in the secondary transfer section. The recording material S with the transferred toner image is then transported to the fixing roller pair 19. The fixing roller pair 19 heats and pressurizes the toner image on the recording material S, fixing it to the recording material S. After that, the recording material S is discharged onto the discharge tray 21 by the discharge roller pair 20.

[0020] In the image forming process described above, if the rotation of the photosensitive drum 2 becomes unstable, the image quality deteriorates, so it is preferable for the photosensitive drum 2 to rotate at a constant speed. In the image forming apparatus 1 of this embodiment, a so-called cleanerless configuration is employed in which the toner remaining on the photosensitive drum 2 is recovered by the developing roller 5. Therefore, compared to a configuration in which the toner remaining on the photosensitive drum 2 is removed by a cleaning member such as a cleaning blade, the torque required for the photosensitive drum 2 to rotate is small.

[0021] <First Example> <Drive configuration> Next, the drum drive unit, which acts as a rotating body drive unit, will be described in detail. The drum drive unit includes the drive train described below. In this embodiment, the drum drive unit drives multiple photosensitive drums 2 as multiple rotating bodies.

[0022] Figures 2(a) and 2(b) show the drive train (drive force transmission path) of this embodiment. Figure 2(a) is a perspective view of the drive train, showing the drive force transmission path from motor 200 to photosensitive drum 2K and photosensitive drum 2C. Figure 2(b) is a component diagram showing the inside of the drive stabilization unit G in Figure 2(a).

[0023] In the first embodiment, the drum drive units for photosensitive drum 2M and photosensitive drum 2Y are the same as those for photosensitive drum 2K and photosensitive drum 2C, which will be described below, so their description will be omitted.

[0024] The configuration of the drum drive unit for the photosensitive drum 2K (first photosensitive drum) as the first rotating body and the photosensitive drum 2C (second photosensitive drum) as the second rotating body will be described. The drum drive unit includes a motor 200 as a drive source, a pinion gear 207, a drum gear 201C, a drum gear 201K, idler stage gears (202C, 202K), and an attachment gear 203. The pinion gear 207 is attached to the output shaft of the motor 200 and is an example of an output transmission member. The output shaft of the motor 200 may have a gear shape corresponding to the pinion gear 207.

[0025] Motor 200 generates a driving force to drive the photosensitive drum 2. Pinion gear 207 is fixed to the output shaft of motor 200 by press-fitting. Drum gear 201C is connected to the photosensitive drum 2C. In this embodiment, drum gear 201C has a coupling portion (first coupling) 201aC (201a) that engages with the photosensitive drum 2C. Drum gear 201C is an example of a first gear (first transmission member) that engages with the first adjustment gear 204, which will be described later. Drum gear 201C rotates the photosensitive drum 2 in the direction of the arrow in Figure 2(a). Drum gear 201K is connected to the photosensitive drum 2K. In this embodiment, drum gear 201K has a coupling portion (second coupling) 201aK (201a) that engages with the photosensitive drum 2K. Attachment gear 203 is fixed to drum gear 201K. In other words, the drum gear 201K and the attachment gear 203 are integrated. The integrated component (gear) of the drum gear 201K and the attachment gear 203 is an example of a second gear (second transmission member) that engages with the second adjustment gear 205, which will be described later. The idler stage gear 202C engages with the pinion gear 207 and the drum gear 201C. The idler stage gear 202K engages with the pinion gear 207 and the drum gear 201K. The coupling portion 201a is configured to engage with the photosensitive drum 2 and transmit the driving force of the motor 200 to the photosensitive drum 2. The coupling portion 201a may be detachably engaged with the photosensitive drum 2.

[0026] The coupling portion 201a is configured to engage with the photosensitive drum 2 and transmit the driving force of the motor 200 to the photosensitive drum 2. The coupling portion 201a is removably engaged with the photosensitive drum 2. Note that each photosensitive drum (2C, 2K) and each drum gear (201C, 201K) may be inseparably integrated.

[0027] Referring to Figure 2(b), the configuration of the drive stabilization unit G will be described.

[0028] The drive stabilization unit G includes a first adjustment gear 204, a second adjustment gear 205, and a torsion coil spring (hereinafter referred to as the spring) 206. The first adjustment gear 204 meshes with the drum gear 201C. An example of a third gear (third transmission member) that engages with the second gear (second transmission member). The second adjustment gear 205 is an example of a fourth gear (fourth transmission member) that meshes with the attachment gear 203 of the second gear (second transmission member). The first adjustment gear 204 is away from the second transmission members (attachment gear 203 and drum gear 201K) and does not mesh with these second transmission members. The second adjustment gear 205 is away from the drum gear 201C and does not mesh with the drum gear 201C. A spring 206 is attached to the first adjustment gear 204 and the second adjustment gear 205 and generates a spring force. More specifically, the first arm of the spring 206 is held in the spring attachment portion 204a of the first adjustment gear 204, and the second arm of the spring 206 is held in the spring attachment portion 205a of the second adjustment gear 205. The spring 206 is a biasing member that biases one of the first adjustment gear 204 and the second adjustment gear 205 in the CCW (first rotation direction) and the other in the CW direction (second rotation direction) opposite to the CCW (first rotation direction). In this embodiment, the spring 206 biases the first adjustment gear 204 in the CW direction and the second adjustment gear 205 in the CCW direction. The spring force (biasing force) of the spring 206 is applied from the first adjustment gear 204 to the drum gear 201C in the direction of the dotted arrow CW (second rotation direction) in Figure 2(b). The spring force (biasing force) of the spring 206 is applied from the second adjustment gear 205 to the attachment gear 203 in the direction of the dotted arrow CCW (first rotation direction), which is opposite to the dotted arrow CW.

[0029] The spring force acting on the first adjustment gear 204 increases the rotational load on the drum gear 201C. On the other hand, the spring force acting on the second adjustment gear 205 reduces the rotational load on the drum gear 201K. Furthermore, the first adjustment gear 204 and the second adjustment gear 205 rotate at the same speed around a predetermined axis of rotation in the direction of the solid arrow in Figure 3(b) (first rotation direction).

[0030] The first adjustment gear 204 and the second adjustment gear 205 are connected by a spring 206 and rotate in the same direction at the same rotational speed (revolutions per unit time) around a common axis of rotation. As a result, the spring pressure of the spring 206 is kept almost constant while the first adjustment gear 204 and the second adjustment gear 205 are rotating. The ratio of the rotational speeds (ratio of rotational speeds) of the first adjustment gear 204 and the drum gear 201C is the same as the ratio of the rotational speeds (ratio of rotational speeds) of the second adjustment gear 205 and the drum gear 201K. In this embodiment, since the rotational speed, number of teeth, and module of the drum gear 201C and the attachment gear 203 are the same, the first adjustment gear 204 and the second adjustment gear 205 are configured with the same number of teeth. At least one of the drum gear 201C and the attachment gear 203 may be a shift gear, and at least one of the first adjustment gear 204 and the second adjustment gear 205 may be a shift gear. Furthermore, if the rotational speeds of the first adjustment gear 204 and the second adjustment gear 205 are the same, it is possible to adjust the module and configure it with different numbers of teeth.

[0031] The drive state of the gears during image formation will be explained using Figure 3. Figures 3(a), (b), (c), and (d) are enlarged views showing the meshing state of the gears in the drive train. Figures 3(a) and 3(c) are enlarged views showing the meshing state of section E in Figure 2(a), between the drum gear 201C and the idler stage gear 202C. Figures 3(b) and 3(d) are enlarged views showing the meshing state of section F in Figure 2(a), between the drum gear 201K and the idler stage gear 202K.

[0032] During image formation, driving force is transmitted from the motor 200 to each photosensitive drum 2. As explained earlier, the surface speed of the transfer belt 14 is faster than the surface speed of the photosensitive drum 2. Therefore, the photosensitive drum 2 receives a force from the transfer belt 14 in the direction that increases its rotational speed (leading rotation direction). The amount of toner on the photosensitive drum 2 causes the leading rotation force received by the photosensitive drum 2 from the transfer belt 14 to fluctuate. If the force received by the photosensitive drum 2 from the transfer belt 14 exceeds the rotational load on the photosensitive drum 2, a phenomenon may occur where the rotational speed of the photosensitive drum 2 becomes faster than the rotational speed of the photosensitive drum 2 driven by the motor 200 (leading rotation).

[0033] Assuming that the drive stabilization unit G described earlier is absent, the preceding photosensitive drum 2 When rotation occurs, a pre-rotation state occurs in the drum gears 201C and 201K, as shown in Figures 3(a) and 3(b). That is, the drum gears 201C and 201K separate from the gear tooth surfaces of the idler stage gears 202C and 202K, respectively, and the rotation of the photosensitive drums 2C and 2K becomes unstable. As a result, image quality (uniformity of image density) may decrease.

[0034] Next, the driving state of the photosensitive drum 2 when the drive stabilization unit G, which is the configuration of this disclosure, is arranged will be described. First, the driving of the photosensitive drum 2C will be described. As shown in Figure 3(c), the drum gear 201C receives a spring force from the first adjustment gear 204 in the direction of the dotted arrow in Figure 3(c). The spring force is greater than the force that the photosensitive drum 2C receives from the transfer belt 14 and the force required for the photosensitive drum 2K to rotate (rotational load). Therefore, the drum gear 201C rotates in contact with the downstream tooth surface 202Ca of the idler stage gear 202C without separating from it. The downstream tooth surface 202Ca of the idler stage gear 202C is the tooth surface facing downstream in the rotation direction of the idler stage gear 202C. The meshing relationship between the idler gear 202C and the pinion gear 207 is the same as the meshing relationship between the drum gear 201C and the idler gear 202C shown in Figure 3(c). In other words, the idler gear 202C receives spring force from the drum gear 201C and contacts the downstream tooth surface of the pinion gear 207 (the surface facing downstream in the rotational direction of the pinion gear 207) without separating from the pinion gear 207. As a result, even when the photosensitive drum 2C is subjected to force in the preceding rotational direction, the contact state of each gear is maintained. In other words, the state in which each gear rotates according to the speed of the motor 200 is maintained. As a result, the rotational speed of the photosensitive drum 2C by the motor 200 is maintained, and the photosensitive drum 2C can rotate at a constant speed.

[0035] Next, the driving state of the photosensitive drum 2K will be described. As shown in Figure 3(d), the drum gear 201K receives a spring force from the second adjustment gear 205 via the attachment gear 203 in the direction of the dotted arrow in Figure 3(d). The spring force is greater than the rotational load of the photosensitive drum 2K. Therefore, the drum gear 201K rotates in contact with the upstream tooth surface 202Kb of the idler stage gear 202K without separating from it. The upstream tooth surface 202Kb of the idler stage gear 202K is the surface facing upstream in the rotational direction of the idler stage gear 202K. The relationship of the meshing portion between the idler stage gear 202K and the pinion gear 207 is the same as the relationship of the meshing portion between the drum gear 201K and the idler stage gear 202K shown in Figure 3(d). In other words, the idler gear 202K receives spring force from the drum gear 201K and remains in contact with the upstream tooth surface of the pinion gear 207 (the surface facing upstream in the direction of rotation of the pinion gear 207) without separating from it. As a result, even when the photosensitive drum 2K is subjected to force in the preceding rotational direction, the contact state of each gear is maintained. In other words, each gear maintains a state in which it rotates according to the speed of the motor 200. As a result, the rotational speed of the photosensitive drum 2K by the motor 200 is maintained, and the photosensitive drum 2K can rotate at a constant speed.

[0036] In this way, the meshing state of each gear is maintained by the spring 206. Therefore, even if the magnitude of the force acting on the photosensitive drum 2 changes, rotational fluctuations of the photosensitive drum 2 are suppressed. In this embodiment, drum gear 201K and drum gear 201C were connected to photosensitive drum 2C and photosensitive drum 2K, but gears corresponding to idler stage gear 202C and idler stage gear 202K may be connected to photosensitive drum 2C and photosensitive drum 2K. In other words, in the drive train, gears other than drum gear 201K and drum gear 201C in this embodiment may have a configuration corresponding to the coupling part described above.

[0037] In this embodiment, the idler gear 202C, pinion gear 207, and idler gear 202K are examples of connection parts (intermediate transmission parts) that connect the drum gear 201C (first transmission member) and the drum gear 201K to the attachment gear 203 (second transmission member). By connecting the connection parts to the first transmission member and the second transmission member, the first transmission member, the second transmission member, the drive stabilization unit G (first adjustment gear 204 (third transmission member)), and the spring 206 (biasing member) are connected. A closed-loop drive train is formed, including the second adjustment gear 205 (fourth transmission member). The pinion gear 207 is an output transmission member driven by the motor 200 as the drive source, and is included in the drive train (more specifically, the connection part). The connection part may contain one or more gears. Also, although the pinion gear 207 is an example of an output transmission member, the output transmission member does not have to be directly connected to the shaft of the motor 200.

[0038] Furthermore, in this embodiment, a configuration is adopted in which the first adjustment gear 204 (third transmission member) and the second adjustment gear 205 (fourth transmission member) are arranged coaxially. Also, in this embodiment, the number of teeth of the drum gear 201C (first transmission member) and the number of teeth of the attachment gear 203 of the second transmission member are the same. Also, the number of teeth of the first adjustment gear 204 that meshes with the drum gear 201C and the number of teeth of the second adjustment gear 205 that meshes with the attachment gear 203 are the same. In other words, the first transmission member has multiple first teeth, the second transmission member has multiple second teeth, the third transmission member has multiple third teeth that mesh with multiple first teeth, and the fourth transmission member has multiple fourth teeth that mesh with multiple second teeth. The number of teeth of the multiple third teeth and the number of teeth of the multiple fourth teeth are the same, and the number of teeth of the multiple first teeth and the number of teeth of the multiple second teeth are the same.

[0039] The spring 206 may bias the first adjustment gear 204 in the CCW direction and the second adjustment gear 205 in the CW direction. In this case, the first adjustment gear 204 applies a spring force to the drum gear 201C in the CCW direction, and the second adjustment gear 205 applies a spring force from the spring 206 to the attachment gear 203 in the CW direction. In this case, the drum gear 201C rotates in contact with the upstream tooth surface of the idler gear 202C (the tooth surface facing upstream in the direction of rotation of the idler gear 202C) without separating from the idler gear 202C. Also, the idler gear 202C contacts the upstream tooth surface of the pinion gear 207 (the surface facing upstream in the direction of rotation of the pinion gear 207) without separating from the pinion gear 207. The drum gear 201K rotates in contact with the downstream tooth surface of the idler gear 202K (the tooth surface facing downstream in the direction of rotation of the idler gear 202K) without separating from it. Similarly, the idler gear 202K remains in contact with the downstream tooth surface of the pinion gear 207 (the surface facing downstream in the direction of rotation of the pinion gear 207) without separating from it. Even in this case, the meshing state of each gear is maintained by the spring 206. Therefore, even if the magnitude of the force acting on the photosensitive drum 2 changes, rotational fluctuations of the photosensitive drum 2 are suppressed.

[0040] As explained above, the unstable state caused by pre-rotation when the rotational load on the photosensitive drum is small is suppressed, and it becomes possible to maintain a constant rotational speed of the photosensitive drum. Therefore, the deterioration of image quality can be suppressed. Furthermore, with the configuration of this embodiment, it is possible to maintain a constant rotational speed of the photosensitive drum without adding a flywheel or the like to deliberately increase the rotational load on the photosensitive drum. Therefore, it is easier to miniaturize the motor 200 and reduce its torque.

[0041] <Second Example> The second embodiment differs from the first embodiment only in its drive configuration. Therefore, only the drive configuration will be described, and the parts that overlap with the first embodiment will be omitted.

[0042] <Drive configuration> The drum drive unit as a rotating body drive unit in the second embodiment will be described in detail with reference to Figures 4(a), 4(b), and 5(a).

[0043] Figures 4(a) and 4(b) show the drum drive unit of this embodiment. Figure 4(a) is a perspective view of the drum drive unit of the second embodiment. In the second embodiment, one motor 400 is used as the drive source to rotate four photosensitive drums (2K, 2C, 2M, 2Y) and the drive roller 15. This is the configuration. In this embodiment, three drive stabilization units (G1, G2, G3) are arranged to prevent each photosensitive drum 2 from rotating ahead of the others.

[0044] Figures 5(a), (b) and 6(a), (b) are schematic diagrams showing the drive train of this embodiment. The drive train of this embodiment includes drum gears (402Y, 402M, 402C, 402K), idler stage gear 403, idler stage gear 404, idler gears 405, 406, 407, and attachment gears 412M and 412K. Furthermore, the drive train of this embodiment includes drive stabilization units G1, G2, and G3. Idler gear 406 meshes with pinion gear 401. Pinion gear 401 is fixed to the shaft of motor 400 by press-fitting. The drum gears (402K, 402C, 402M, 402Y) are connected to each photosensitive drum (2K, 2C, 2M, 2Y) and rotate each photosensitive drum in the direction of the arrow in Figure 5(a). Idler gear 403 meshes with drum gears 402Y and 402M. Idler gear 404 meshes with drum gears 402C and 402K. Idler gear 405 meshes with idler gear 406 and idler gear 403, and idler gear 407 meshes with idler gear 406 and idler gear 404. Attachment gear 412M is integrated with drum gear 402M. Attachment gear 412K is integrated with drum gear 402K.

[0045] Figure 4(b) shows the drive stabilization unit. Note that drive stabilization unit G1 and drive stabilization units G2 and G3 have the same configuration.

[0046] The drive stabilization units G1, G2, and G3 each have a first adjustment gear 413, a second adjustment gear 414, and a torsion coil spring 415. The first arm of the torsion coil spring 415 is held by the spring attachment portion 413a of the first adjustment gear 413, and the second arm of the torsion coil spring 415 is held by the spring attachment portion 414a of the second adjustment gear 414. The relationship between the first adjustment gear 413, the second adjustment gear 414, and the torsion coil spring 415 is the same as the relationship between the first adjustment gear 204, the second adjustment gear 205, and the spring 206 in the drive stabilization unit G of Embodiment 1. In other words, the torsion coil spring 415 biases one of the first adjustment gear 413 and the second adjustment gear 414 in the first rotation direction, and biases the other of the first adjustment gear 413 and the second adjustment gear 414 in the second rotation direction opposite to the first rotation direction.

[0047] The first adjustment gear 413 and the second adjustment gear 414 rotate at the same speed around a predetermined rotation axis. The configurations of the drive stabilization units G1, G2, and G3 are the same as those of the drive stabilization unit G in Embodiment 1, so a detailed explanation is omitted.

[0048] The drive unit for rotating the transfer belt 14 includes a drive roller gear 408 and idler gears 409, 410, and 411. The drive roller gear 408 is arranged coaxially with the drive roller 15 and drives the drive roller 15. The idler gears 409, 410, and 411 are configured to transmit the driving force from the motor 400 to the drive roller gear 408.

[0049] The driving state during image formation will be explained using Figures 6(a) and 6(b).

[0050] As shown by the solid line in Figure 6(a), a closed-loop drive train is formed including the idler stage gear 403, drum gear 402Y, drive stabilization unit G1, drum gear 402M, and attachment gear 412M. In the relationship shown in Figure 6(a), the drum gear 402Y is an example of the first transmission member, and the member (gear) in which the drum gear 402M and attachment gear 412M are integrated is an example of the second transmission member. The first adjustment gear 413 is an example of the third transmission member, engaging (meshing) with the first transmission member and being separated from the second transmission member. The second adjustment gear 414 is an example of the fourth transmission member, engaging (meshing) with the second transmission member and being separated from the first transmission member. The second adjustment gear 414 meshes with the attachment gear 412M. The idler stage gear 403 is a connecting part (intermediate transmission) that connects the first transmission member and the second transmission member. This is an example of a part. The idler stage gear 403 is also an example of an output transmission member. The relationship between the spring force of the torsion coil spring 415, the rotational load of the photosensitive drum 2, and the force that the photosensitive drum 2 receives from the transfer belt 14 is the same as that shown in Example 1.

[0051] In Figures 5(b), 6(a), and 6(b), mark 601 indicates the portion where a spring force acts from one gear to the other, and one gear contacts the downstream tooth surface of the other gear (the tooth surface facing downstream in the rotational direction of the other gear). Mark 602 indicates the portion where a spring force acts from one gear to the other, and one gear contacts the upstream tooth surface of the other gear (the tooth surface facing upstream in the rotational direction of the other gear). The drum gear 402Y receives a spring force from the first adjustment gear 413 in the direction of the dotted arrow in Figure 6(a). On the other hand, the drum gear 402M receives a spring force from the second adjustment gear 414 via the attachment gear 412M in the direction of the dotted arrow in Figure 6(a). Therefore, even if the force acting on the photosensitive drum fluctuates, contact between the drum gear 402Y and the idler stage gear 403 is maintained, and contact between the drum gear 402M and the idler stage gear 403 is maintained.

[0052] The idler gear 403, drum gear 402Y, drive stabilization unit G1, drum gear 402M, and attachment gear 412M are driven according to the speed of motor 400.

[0053] The relationship between the idler gear 403, drum gear 402Y, drive stabilization unit G1, drum gear 402M, and attachment gear 412M can be said to be the same as the relationship between the drum drive unit in Embodiment 1.

[0054] As shown by the solid lines in Figure 6(b), a closed-loop drive train is formed, including idler gear 406, idler gear 405, idler stage gear 403, drum gear 402M, attachment gear 412M, drive stabilization unit G2, drum gear 402C, idler stage gear 404, and idler gear 407. In the relationship shown in Figure 6(b), the integrated member (gear) of drum gear 402M and attachment gear 412M is an example of a first transmission member, and drum gear 402C is an example of a second transmission member. The second adjustment gear 414 is an example of a third transmission member, engaging (meshing) with the first transmission member and disengaging from the second transmission member. The second adjustment gear 414 meshes with the attachment gear 412M. The first adjustment gear 413 is an example of a fourth transmission member, engaging (meshing) with the second transmission member and disengaging from the first transmission member. Idler gears 406, 405, 403, 404, and 407 are examples of connection points (intermediate transmission points) that connect the first transmission member and the second transmission member. Idler gear 406 is an example of an output transmission member.

[0055] The relationship between the spring force of the torsion coil spring 415, the rotational load of the photosensitive drum 2, and the force that the photosensitive drum 2 receives from the transfer belt 14 is the same as that shown in Example 1. The drum gear 402C receives a spring force from the first adjustment gear 413 in the direction of the dotted arrow in Figure 6(b). The spring force is greater than the force that the photosensitive drum 2C receives from the transfer belt 14. Therefore, the drum gear 402C rotates without separating from the idler stage gear 404. On the other hand, the drum gear 402M receives a spring force from the second adjustment gear 414 via the attachment gear 412M in the direction of the dotted arrow in Figure 6(a). The spring force is greater than the rotational load of the photosensitive drum 2M. Therefore, the drum gear 402M rotates without separating from the idler stage gear 403.

[0056] The spring force also acts between idler gear 406, idler gear 405, idler stage gear 403, idler stage gear 404, and idler gear 407. Therefore, the meshing state of each gear is maintained.

[0057] Idler gear 406, idler gear 405, idler stage gear 403, drum gear 402M, attachment gear 412M, drive stabilization unit G2, drum gear 402C, i The drum gear 404 and idler gear 407 are driven according to the speed of the motor 400. The relationship between idler gear 406, idler gear 405, idler gear 403, drum gear 402M, attachment gear 412M, drive stabilization unit G2, drum gear 402C, idler gear 404, and idler gear 407 can be said to be the same as the relationship between the drum drive unit in Embodiment 1.

[0058] The drive stabilization unit G3 is the same as the drive stabilization unit G1, so we will omit its explanation.

[0059] Furthermore, the idler gear 406 is subjected to the rotational load of the drive roller 15. As a result, the idler gear 406 maintains contact with the downstream tooth surface of the pinion gear 401 (the tooth surface facing downstream in the direction of rotation of the pinion gear 401). The rotational load of the drive roller 15 increases the rotational load on the idler gear 406. Therefore, the rotational load on the idler gear 406 is higher than the force acting on the idler gear 406 when the photosensitive drum 2 receives a force from the transfer belt 14 in the leading rotation direction. Consequently, the idler gear 406 does not separate from the pinion gear 401.

[0060] Figure 5(b) shows the direction of rotation of each gear and the direction of the torque acting on each gear. The solid arrows indicate the direction of rotation, and the dotted arrows indicate the direction of the torque acting on each gear. As shown in Figure 5(b), each gear stably contacts either the upstream or downstream tooth surface of the mating gear. As a result, it is possible to rotate each gear and the photosensitive drum at a constant speed corresponding to the speed of the motor 400.

[0061] As explained above, compared to the first embodiment, even with a configuration in which one motor rotates four photosensitive drums and a transfer belt, rotational fluctuations of the photosensitive drum 2 are suppressed.

[0062] As shown in this embodiment, the drive train according to the present disclosure may include a plurality of closed-loop drive trains.

[0063] <Third Example> The third embodiment shows a case in which the configuration of the present disclosure is adopted in a monochrome laser printer that uses only one photosensitive drum. Therefore, the explanation of parts that overlap with the first embodiment is omitted.

[0064] <Overall Outline Diagram> Figure 7 is a cross-sectional view of an image forming apparatus 700 according to the third embodiment. As an example of an image forming apparatus, a monochrome laser beam printer using an electrophotographic process is shown. The feeding unit, fixing unit, and paper discharge unit have the same configuration as the color laser beam printer of the first embodiment, so a detailed explanation is omitted.

[0065] The image forming apparatus 700 includes a process cartridge 701 that is detachable from the apparatus body.

[0066] The image forming unit is provided with a charging roller 703 that uniformly charges the surface of the photosensitive drum 2, and a developing roller 702 that supplies toner to the electrostatic latent image formed on the photosensitive drum 2 and develops it as a toner image. A laser scanner 704 is positioned on top of the photosensitive drum 2 as an exposure means. It consists of a transfer roller 705 that transfers the toner image from the photosensitive drum 2 to the recording material S, and a pair of fixing rollers 706 that fix the toner on the recording material S. The developing roller 702 is provided in this process cartridge 701. Note that the process cartridge 701 may include the photosensitive drum 2 and the charging roller 703, or it may also include the transfer roller 705.

[0067] The image formation process will now be described. The photosensitive drum 2 is driven at a predetermined rotational speed in the clockwise direction as shown in Figure 7. The charging roller 703 uniformly charges the surface of the rotating photosensitive drum 2. Laser light L corresponding to the image information is emitted from the laser scanner 704, and the surface of the photosensitive drum 2 is exposed. This forms an electrostatic latent image corresponding to the image information on the surface of the photosensitive drum 2. This electrostatic latent image is developed as a toner image by the developing roller 702. This toner image is then transferred by the transfer roller 705 to the recording material S, which is transported to the nip between the photosensitive drum 2 and the transfer roller 705. The recording material S with the transferred toner image is transported to the fixing roller pair 706. The fixing roller pair 706 heats and pressurizes the toner image on the recording material S and fixes it to the recording material S. The developer remaining on the photosensitive drum 2 is recovered by the developing roller 702.

[0068] In this embodiment as well, since no cleaning member such as a cleaning blade is in contact with the photosensitive drum 2, the rotational load torque of the photosensitive drum 2 is low. Therefore, for example, thermal expansion of the fixing roller pair 706 may increase the transport speed of the recording material S, causing the recording material S sandwiched between the photosensitive drum 2 and the transfer roller 705 to be pulled, which may result in the photosensitive drum 2 rotating ahead of schedule.

[0069] <Drive configuration> The drum drive unit will be explained in detail.

[0070] Figures 8(a) and 8(b) show the drive train of this embodiment. Figure 8(a) is a perspective view of the drum drive unit, showing the drive transmission section from the motor 800 to the photosensitive drum 2. Figure 8(b) is a parts diagram showing the inside of the drive stabilization unit G4 in Figure 8(a).

[0071] The drum drive unit of this embodiment includes a motor 800, a pinion gear 801, a drum gear 802, an idler gear 803, and a drive stabilization unit G4. The motor 800 is a drive source that generates driving force to drive the photosensitive drum 2. The pinion gear 801 is fixed to the shaft of the motor 800 by press-fitting. The drum gear 802 is connected to the photosensitive drum 2 and rotates the photosensitive drum 2 in the direction of the arrow in Figure 8(a). The drum gear 802 has the same configuration as the drum gear 201C, etc. in Embodiment 1. The idler gear 803 meshes with the pinion gear 801 and the drum gear 802.

[0072] Referring to Figure 8(b), the configuration of the drive stabilization unit G4 will be described.

[0073] The drive stabilization unit G4 includes a first adjustment gear 804, a second adjustment gear 805, and a torsion coil spring 806. The first arm of the torsion coil spring 806 is held by the spring attachment portion 804a of the first adjustment gear 804, and the second arm of the torsion coil spring 806 is held by the spring attachment portion 805a of the second adjustment gear 805. The relationship between the first adjustment gear 804, the second adjustment gear 805, and the torsion coil spring 806 is the same as the relationship between the first adjustment gear 204, the second adjustment gear 205, and the torsion coil spring 206 in the drive stabilization unit G of Embodiment 1. In other words, the torsion coil spring 806 biases one of the first adjustment gear 804 and the second adjustment gear 805 in the first rotational direction, and biases the other of the first adjustment gear 804 and the second adjustment gear 805 in the second rotational direction opposite to the first rotational direction.

[0074] In this way, a closed-loop drive train is formed, including a pinion gear 801, a drum gear 802, an idler stage gear 803, and a drive stabilization unit G4. The drum gear 802 is an example of a first transmission member, and the pinion gear 801 is an example of a second transmission member. The first regulating gear 804 is an example of a third transmission member, meshing with the drum gear 802 and away from the pinion gear 801. The second regulating gear 805 is an example of a fourth transmission member, meshing with the pinion gear 801, It is separated from the drum gear 802. The idler stage gear 803 is an example of a connection (intermediate transmission) that connects the drum gear 802 and the pinion gear 801 so that a closed-loop drive train is formed. The pinion gear 801 is an example of an output transmission member.

[0075] Furthermore, the first adjustment gear 804 and the second adjustment gear 805 rotate at the same speed around a predetermined rotation axis in the direction of the solid line in Figure 8(b). Therefore, even while rotating, it is possible to maintain the spring pressure of the torsion coil spring 806 at a nearly constant level. The configuration of the drive stabilization unit G4 is the same as that of the drive stabilization unit in the first embodiment, so a detailed explanation is omitted.

[0076] In this embodiment, the spring force maintains contact between the pinion gear 801, idler gear 803, drum gear 802, first adjustment gear 804, and second adjustment gear 805. As a result, stable rotation of the photosensitive drum 2 becomes possible.

[0077] As explained above, even with only one photosensitive drum, it can rotate at a constant speed without generating any preceding rotation.

[0078] Furthermore, in the configuration of this embodiment, there is no need to use components that increase the rotational load, such as a flywheel.

[0079] <Fourth Example> A fourth embodiment will be described. In the fourth embodiment, a configuration for releasing the biasing of the biasing member in the drive stabilization unit will be described. The fourth embodiment will be described as a modification of the second embodiment, but it can also be combined with the first and third embodiments.

[0080] For example, if a drive train equipped with a drive stabilization unit is left in a high-temperature environment for an extended period, the biasing force of the biasing member may cause deformation of at least one of the first, second, third, and fourth transmission members, potentially reducing the rotational accuracy of these members.

[0081] For example, when an image forming apparatus is being transported, it may be exposed to a high-temperature environment for an extended period. In this embodiment, when the image forming apparatus is not in use, the biasing of the biasing member in the drive stabilization unit is released. As a result, for example, when the image forming apparatus is being transported, deformation of the first transmission member, second transmission member, third transmission member, and fourth transmission member is suppressed.

[0082] When the image forming apparatus is used, the biasing member biases the third and fourth transmission members. As a result, the image forming operation on the recording material is performed with the biasing member biasing the third and fourth transmission members.

[0083] In this embodiment, the configuration differs only in the drive stabilization unit compared to the second embodiment; the other parts are the same. Therefore, the configuration and operation of the drive stabilization unit will be described primarily.

[0084] Figures 10(a) and 10(b) show the drive train of this embodiment. Figure 10(a) shows the drive train of this embodiment having drive stabilization units (G10, G20, G30). The configurations of drive stabilization units G10, G20, and G30 are identical.

[0085] The left side of Figure 10(b) is a perspective view of the drive stabilization units G10, G20, and G30.

[0086] The right side of Figure 10(b) shows exploded views of the drive stabilization units G10, G20, and G30. As mentioned above, the configurations of the drive stabilization units G10, G20, and G30 are identical. However, in the following explanation, these will not be distinguished and will simply be referred to as drive stabilization units.

[0087] As shown in Figure 10(b), the drive stabilization unit has a first adjustment gear 1002 as a third transmission member, a compression spring 1004, and a second adjustment gear 1005 as a fourth transmission member. Furthermore, the drive stabilization unit has a force-applying cam 1003 and a release cam 1001 as a release means (release member), and a shaft 1006 that supports the first adjustment gear 1002, the force-applying cam 1003, and the second adjustment gear 1005. In this embodiment, the material of the first adjustment gear 1002, the drum gear that meshes with the first adjustment gear 1002, the second adjustment gear 1005, and the drum gear that meshes with the second adjustment gear 1005 is resin. The recess 1003b of the force-applying cam 1003 engages with the protrusion 1005a of the second adjustment gear 1005. The relative movement of the force-applying cam 1003 and the second adjustment gear 1005 is restricted in the rotational direction (direction of arrow A in the figure). On the other hand, the force-applying cam 1003 and the second adjustment gear 1005 are able to move relative to each other in the direction of the rotation axis of the second adjustment gear 1005 (direction of arrow B in the figure). As will be described later, the compression spring 1004 and the force-applying cam 1003 function as biasing members that bias one of the third transmission member and the fourth transmission member in the first rotation direction, and the other in the second rotation direction opposite to the first rotation direction. Similar to the second embodiment, the first adjustment gear 1002 and the second adjustment gear 1005 mesh with different drum gears. If the image forming apparatus is left in a high-temperature environment for a long time, deformation of the first adjustment gear 1002 and the drum gear meshing with the first adjustment gear 1002 may occur, and deformation of the second adjustment gear 1005 and the drum gear meshing with the second adjustment gear 1005 may also occur. The first adjustment gear 1002 and the second adjustment gear 1005 have the same rotational speed.

[0088] <Operation Description> Next, the operation of the drive stabilization unit will be explained using Figures 11(a) to (d). Figures 11(a) to (d) show the operation of the drive train in this embodiment. Figure 11(a) shows the release cam 1001 separated from the first adjustment gear 1002. Figure 11(b) shows the release cam 1001 rotated from the position shown in Figure 11(a). Figure 11(c) shows the retraction of the release cam 1001. Figure 11(d) shows the release cam 1001 in the retracted position. For explanatory purposes, some parts of the first adjustment gear 1002 are omitted from the illustration in Figures 11(a) to (d).

[0089] In the rotational axis direction of the second adjustment gear 1005, one end of the release cam 1001 is provided with a side plate abutment portion 1001a, and the other end of the release cam 1001 is provided with a cam pressing portion 1001b. As shown in Figure 11(a), the side plate abutment portion 1001a of the release cam 1001 abuts against the drive side plate 1000. In this embodiment, the release cam 1001 has three side plate abutment portions 1001a, but the number of side plate abutment portions 1001a may be one or two. Also, the number of side plate abutment portions 1001a may be more than three. The cam pressing portion 1001b abuts against the force-applying cam 1003 and presses the force-applying cam 1003. As will be described later, the biasing force from the compression spring 1004 is applied to the first adjustment gear 1002 via the force-applying cam 1003. On the other hand, in the state shown in Figure 11(a), a gap 1003a is formed between the force-applying cam 1003 and the first adjustment gear 1002, and the biasing force from the compression spring 1004 is not transmitted to the first adjustment gear 1002. In other words, the biasing force of the compression spring 1004 applied to the first adjustment gear 1002 is released. As a result, deformation of the first adjustment gear 1002 and deformation of the drum gear that meshes with the first adjustment gear 1002 are suppressed. Furthermore, deformation of the second adjustment gear 1005 and deformation of the drum gear that meshes with the second adjustment gear 1005 are also suppressed.

[0090] When the image forming apparatus is used, the motor 400 is driven when power is supplied to the image forming apparatus. As a result, the first adjustment gear 1002 and the second adjustment gear 1005 rotate. Meanwhile, the drive side plate 1000 is provided with a release cam retraction hole 1000a. Release cam retraction hole 100 The number of 0a is the same as the number of side plate abutment portions 1001a. When the release cam 1001 rotates together with the second adjustment gear 1005 and the force application cam 1003, the side plate abutment portions 1001a align with the release cam retraction holes 1000a.

[0091] The force of the compression spring 1004 causes the side plate abutment portion 1001a of the release cam 1001 to be inserted into the release cam retraction hole 1000a. At this time, the rotation of the release cam 1001 stops. Meanwhile, the force-applying cam 1003, which was being pushed by the release cam 1001, moves so that the gap 1003a disappears and comes into contact with the first adjustment gear 1002. In other words, it transitions from a released state where the biasing force of the biasing member is released to a biased state where a biasing force is applied.

[0092] The biasing force from the compression spring 1004 acts in the direction of the rotation axis of the second adjustment gear 1005 and the first adjustment gear 1002. The force-applying cam 1003 also has an inclined surface that contacts the first adjustment gear 1002. In this embodiment, the first adjustment gear 1002 also has an inclined surface that contacts the inclined surface of the force-applying cam 1003. The relative movement of the force-applying cam 1003 and the second adjustment gear 1005 is restricted in the rotational direction. The force-applying cam 1003 is biased by the compression spring 1004, and the inclined surfaces of the force-applying cam 1003 and the first adjustment gear 1002 come into contact with each other, so that the force of the compression spring 1004 acts on the first adjustment gear 1002 in the rotational direction via the force-applying cam 1003. In addition, the force-applying cam 1003 receives a reaction force, so that the second adjustment gear 1005 is biased in the opposite direction to the first adjustment gear 1002. As a result, the first adjustment gear 1002 and the second adjustment gear 1005 are subjected to forces in opposite directions, as indicated by the dotted arrows in Figures 11(b) and (c). Consequently, drive stabilization by the drive stabilization unit becomes possible.

[0093] Furthermore, as the first adjustment gear 1002 and the second adjustment gear 1005 rotate, the release cam 1001 moves toward the drive side plate 1000, as shown in Figure 11(d), to a position where it does not obstruct the rotation of the first adjustment gear 1002. In this embodiment, the first adjustment gear 1002 has an inclined surface that moves the release cam 1001 toward the drive side plate 1000. However, for example, a spring may bias the release cam 1001 toward the drive side plate 1000, and the release cam 1001 may retract when the side plate abutment portion 1001a coincides with the release cam retraction hole 1000a.

[0094] As described above, the force-applying cam 1003 functions as a transmission unit that transmits the force of the compression spring 1004, which acts as a biasing unit, to the first adjustment gear 1002. The force-applying cam 1003 can move between a transmission position in which the force of the compression spring 1004 is transmitted to the first adjustment gear 1002, and a disconnection position (Figure 11(a)) in which the transmission of the compression spring 1004 to the first adjustment gear 1002 is disconnected. When the force-applying cam 1003 is in the transmission position, the biasing members (compression spring 1004 and force-applying cam 1003) bias one of the third transmission member and the fourth transmission member in the first rotational direction, and bias the other in the second rotational direction opposite to the first rotational direction. The release cam 1001 can move between a holding position that holds the force-applying cam 1003 in the disconnection position, and an allowable position in which the force-applying cam 1003 is allowed to be in the transmission position. According to the configuration of this embodiment, deformation of the drive stabilization unit and the gears that mesh with the third and fourth transmission members of the drive stabilization unit is suppressed.

[0095] <Fifth Example> A fifth embodiment will be described. In the fifth embodiment, a configuration for releasing the biasing of the biasing member in the drive stabilization unit will be described. The fifth embodiment will be described as a modification of the second embodiment, but it can also be combined with the first and third embodiments.

[0096] In the fourth embodiment, when the image forming apparatus is not in use, the biasing of the biasing member in the drive stabilization unit is released, and when the image forming apparatus is used, the biasing member biases the third transmission member and the fourth transmission member. However, the drive stabilization unit and the third transmission member of the drive stabilization unit In order to further suppress deformation of the gears that mesh with the transmission member and the fourth transmission member, it is preferable to apply a biasing force only during image formation and release the biasing force after image formation is complete.

[0097] Therefore, in this embodiment, the biasing force of the drive stabilization unit is released by the reverse rotation of the motor 400. As a result, the biasing force of the drive stabilization unit is applied during image formation, and after image formation is completed (after image formation is finished), the biasing force of the drive stabilization unit is released.

[0098] <Structure Description> The configuration of this embodiment differs from that of the second embodiment in the configuration of the drive stabilization unit and drum gear, while the other parts are similar. Therefore, the configuration and operation of the drive stabilization unit and drum gear will be described primarily.

[0099] Figures 12(a), (b), and (c) show the drive train of this embodiment. Figure 12(a) shows the drive train of this embodiment having drive stabilization units (G100, G200, G300). The configurations of drive stabilization units G100, G200, and G300 are identical.

[0100] Figure 12(b) is a perspective view of the drive stabilization unit G100. Figure 12(b) is drawn from a viewpoint where the photosensitive drum 2 is located at the top of the figure. Figure 12(c) is an exploded view of the drive stabilization unit G100.

[0101] As mentioned above, the configurations of the drive stabilization units G100, G200, and G300 are identical. Therefore, the following explanation will be based on the drive stabilization unit G100.

[0102] The drive stabilization unit G100 includes a force-applying gear upper 301 as a third transmission member, a force-applying gear lower 304 as a fourth transmission member, a compression spring 302 as a biasing part, and a force-applying cam 303 as a transmission part. Furthermore, the drive stabilization unit G100 includes a release cam gear 306, a one-way gear 307, an idler gear 305, and a stepped gear 300 as release means (release members). In this embodiment, the force-applying gear upper 301, force-applying gear lower 304, idler gear 305, stepped gear 300, drum gear 402Y, and drum gear 402M are all made of resin. The compression spring 302 and the force-applying cam 303 function as biasing members that bias one of the third and fourth transmission members in a first rotational direction and the other in a second rotational direction opposite to the first rotational direction. The idler gear 305 meshes with the drum gear 402Y and the lower power-applying gear 304, transmitting the driving force of the motor 400 to the lower power-applying gear 304.

[0103] The force-applying cam 303 receives a force from the compression spring 302 in the direction of the rotation axis of the lower force-applying gear 304 (direction of arrow D in Figure 12(a)). The force-applying cam 303 is configured to apply a rotational force to the upper force-applying gear 301.

[0104] The force-applying cam 303 has a recess 303c, and the lower force-applying gear 304 has a protrusion 304a. The engagement of the recess 303c and the protrusion 304a restricts the relative movement of the force-applying cam 303 and the lower force-applying gear 304 in the rotational direction (direction of arrow C in the figure). On the other hand, relative movement is possible between the force-applying cam 303 and the lower force-applying gear 304 in the direction of the rotational axis of the lower force-applying gear 304 (direction of arrow B in the figure). The stepped gear 300 meshes with the upper force-applying gear 301 and the drum gear 402M. As will be described in detail later, the stepped gear 300 transmits the force of the compression spring 302 to the drum gear 402M.

[0105] Note that the lower power-applying gear 304 and the upper power-applying gear 301 have the same rotational speed.

[0106] The release cam gear 306 pushes down the force-applying cam 303. As a result, the inclined surfaces of the force-applying cam 303 and the upper part of the force-applying gear 301 separate, and the force-applying cam 303 is subjected to the biasing force of the compression spring 302. This results in a state where the power is not transmitted to the power-granting gear 301.

[0107] The one-way gear 307 meshes with the release cam gear 306 and rotates during image formation (when motor 400 rotates in the forward direction), but does not rotate when motor 400 rotates in the reverse direction.

[0108] Specifically, the support shaft 308 supports the one-way gear 307, and a rotation stopper 308a is inserted into the frame of the image forming apparatus, restricting movement in the rotational direction.

[0109] The one-way mechanism gear 309 is located inside the support shaft 308 and engages with the one-way gear 307. The one-way mechanism gear 309 allows the one-way gear 307 to rotate relative to the support shaft 308 when the motor 400 is rotating forward. On the other hand, the one-way mechanism gear 309 restricts the one-way gear 307 from rotating relative to the support shaft 308 when the motor 400 is rotating backward.

[0110] Furthermore, the mechanism that allows the rotation of the one-way gear 307 when the motor 400 rotates in the forward direction and restricts the rotation of the one-way gear 307 when the motor 400 rotates in the reverse direction is not limited to the above configuration. A detailed explanation of the configuration of the one-way mechanism gear 309 is omitted, but various configurations can be used for allowing and restricting the rotation of the one-way gear 307.

[0111] <Operation Description> First, we will explain the operation in image formation, that is, the operation of the drive stabilization unit G100 when the motor 400 is rotating in the forward direction. Figures 13(a), (b), (c), and (d) show the operation of the drive train when the motor 400 is rotating in the forward direction.

[0112] As shown in Figure 13(a), when the motor 400 rotates in the forward direction, the pinion gear 401 rotates clockwise in the figure. Furthermore, as shown in Figure 13(a), the relationship between the drive stabilization unit G100, drum gear 402Y, and drum gear 402M is the same as the relationship between the drive stabilization unit G200, drum gear 402M, and drum gear 402C. Also, the relationship between the drive stabilization unit G200, drum gear 402M, and drum gear 402C is the same as the relationship between the drive stabilization unit G300, drum gear 402C, and drum gear 402K.

[0113] Figure 13(b) is an enlarged view of the drive stabilization unit G100, drum gears 402Y and 402M. The dotted arrows in Figure 13(b) indicate the direction of the force acting on each gear. The solid arrows in Figure 13(b) indicate the direction of rotation of each gear.

[0114] Figure 13(c) is a perspective view of the drive stabilization unit G100. The solid arrows in Figure 13(c) indicate the rotation direction of each gear.

[0115] Figure 13(d) is a perspective view of the drive stabilization unit G100. For illustrative purposes, a portion of the force-applying gear 301 is omitted from the illustration. The dotted arrows in Figure 13(d) indicate the direction of the force acting on each gear.

[0116] As mentioned above, the drum gear 402Y meshes with the idler gear 305, and the idler gear 305 meshes with the lower power-applying gear 304. In addition, the drum gear 402M meshes with the stepped gear 300, and the stepped gear 300 meshes with the upper power-applying gear 301.

[0117] The drum gear 402Y and drum gear 402M rotate in the same direction and at the same speed. Also, the upper force-applying gear 301 and the lower force-applying gear 304 rotate in the same direction and at the same peripheral speed. As a result, the relative rotation between the force-applying cam 303 and the upper force-applying gear 301 is suppressed.

[0118] The biasing force from the compression spring 302 acts in the direction of the rotation axis of the lower force-applying gear 304 and the upper force-applying gear 301. The force-applying cam 303 has an inclined surface 303a that contacts the upper force-applying gear 301. Also, as described above, the relative movement of the force-applying cam 303 and the lower force-applying gear 304 is restricted in the rotational direction. The force-applying cam 303 is biased by the compression spring 302, and the inclined surface 303a of the force-applying cam 303 contacts the upper force-applying gear 301, so that the force of the compression spring 302 acts in the rotational direction of the upper force-applying gear 301 via the force-applying cam 303. Also, the force-applying cam 303 receives a reaction force, so that the lower force-applying gear 304 is biased in the opposite direction to the upper force-applying gear 301. As a result, the upper force-applying gear 301 and the lower force-applying gear 304 receive forces in opposite directions from each other due to the compression spring 302. Specifically, as shown in Figure 13(d), the upper force-applying gear 301 receives a force in the direction of the dotted arrow E, and the lower force-applying gear 304 receives a force in the direction of the dotted arrow F. As a result, as shown in Figures 13(b) and (d), the idler gear 305 receives a force in the direction of the dotted arrow G, and the stepped gear 300 receives a force in the direction of the dotted arrow H. Furthermore, the drum gear 402Y receives a force in the direction of the dotted arrow I, and the drum gear 402M receives a force in the direction of the dotted arrow J. As a result, the drive is stabilized by the drive stabilization unit G100.

[0119] On the other hand, as shown in Figure 13(d), the force-applying cam 303 pushes the release cam gear 306 in the rotational direction at the rib 303b. The release cam gear 306 is meshed with the one-way gear 307. When the motor 400 rotates in the forward direction, the one-way gear 307 is allowed to rotate in the direction of the solid arrow K in Figure 13(c). Therefore, the force-applying cam 303, the release cam gear 306, and the one-way gear 307 can each rotate.

[0120] Next, the operation of the drive stabilization unit G100 when the motor 400 rotates in reverse will be explained. Figures 14(a), (b), and (c) show the operation of the drive train when the motor 400 rotates in reverse. The drive stabilization unit G100 can change the state in which the force of the compression spring 302 is not applied to the drum gear 402Y and drum gear 402M by rotating the motor 400 in reverse. Figures 14(a), (b), and (c) show the operation of the G100 unit when the motor 400 rotates in reverse. When the motor 400 starts to rotate in reverse, the force-applying cam 303 transitions in the order shown in Figures 14(a), (b), and (c).

[0121] The force-applying cam 303 and the lower force-applying gear 304 are restricted from relative movement in the rotational direction. When the motor 400 rotates in the reverse direction, the force-applying cam 303 rotates in the direction of arrow L in the figure, in conjunction with the rotation of the lower force-applying gear 304.

[0122] The force-applying cam 303 contacts the inclined surface 306a of the release cam gear 306. On the other hand, as described above, the rotation of the one-way gear 307 meshing with the release cam gear 306 is restricted, and the release cam gear 306 does not rotate. With the release cam gear 306 stopped, the force-applying cam 303 receives a reaction force from the inclined surface 306a of the release cam gear 306. As a result, the force-applying cam 303 is pushed, and the compression spring 302 is compressed. Consequently, a gap is created between the inclined surface 303a on the force-applying cam 303 and the upper part of the force-applying gear 301, so the force of the compression spring 302 is not transmitted to the upper part of the force-applying gear 301. As a result, deformation of the upper part of the force-applying gear 301, the lower part of the force-applying gear 304, the idler gear 305, the stepped gear 300, the drum gear 402Y, and the drum gear 402M is suppressed. In this embodiment, when the motor 400 rotates in the reverse direction, the force-applying cam 303 rides up onto the release cam gear 306, as shown in Figure 14(c).

[0123] As described above, the force-applying cam 303 functions as a transmission unit that transmits the force of the compression spring 302, which acts as a biasing unit, to the force-applying gear 301. The force-applying cam 303 can move between a transmission position in which the force of the compression spring 302 is transmitted to the force-applying gear 301, and a disconnection position in which the transmission of the compression spring 302 to the force-applying gear 301 is disconnected. When the force-applying cam 303 is in the transmission position, the biasing member (compression spring 302 and force-applying cam 303) transmits the third transmission One of the member and the fourth transmission member is biased in a first rotational direction, and the other is biased in a second rotational direction opposite to the first rotational direction. The release cam gear 306 is configured to move the force-applying cam 303 from the transmission position to the disconnection position. In this embodiment, before the image forming apparatus is used, the drive stabilization unit G100 takes the disconnection position (Figure 14(c)). On the other hand, when an image forming operation is performed on the recording material, the motor 400 rotates forward and the force-applying cam 303 is in the transmission position, and after the image forming operation is performed, the motor 400 rotates backward and the force-applying cam 303 is in the disconnection position.

[0124] <Variation> Figures 9(a) and 9(b) show modified drive trains. Figure 9(a) is a perspective view of a drum drive unit according to a modified embodiment of the present disclosure, showing the drive transmission unit from motor 900 to photosensitive drum 2. Figure 9(b) is a parts diagram showing the inside of the drive stabilization unit G5. Matters of this modified embodiment that are not described here are the same as in the above embodiments, and detailed explanations are omitted.

[0125] The drum drive unit of this modified version includes a motor 900, a pinion gear 901, a drum gear 902, idler gears 903, 904, 905, an idler stage gear 906, and a drive stabilization unit G5. The drum drive unit of this modified version further includes a first pulley 911, a second pulley 912, and a timing belt 910. The idler gear 904 includes the second pulley 912.

[0126] Motor 900 generates the driving force to drive the photosensitive drum 2. Pinion gear 901 is fixed to the shaft of motor 900 by press-fitting. Drum gear 902 is connected to the photosensitive drum 2 and has the same configuration as drum gear 201C in Example 1. Drum gear 902 rotates the photosensitive drum 2 in the direction of the arrow in Figure 9(a).

[0127] Referring to Figure 9(b), the configuration of the drive stabilization unit G5 will be described.

[0128] The drive stabilization unit G5 includes a first adjustment gear 907, a second adjustment rotating shaft 908, and a torsion coil spring 909. The drive stabilization unit G5 has the same configuration as the drive stabilization units G1 to G4 shown in the previous embodiments. The second adjustment rotating shaft 908 includes a first pulley 911.

[0129] In this modified example, the drum gear 902 is an example of a first transmission member, and the timing belt 910 is an example of a second transmission member. The first adjusting gear 907 is an example of a third transmission member, meshing with the drum gear 902 and away from the timing belt 910. The second adjusting rotating shaft 908 is an example of a fourth transmission member, with the first pulley 911 meshing with the timing belt 910 and away from the drum gear 902. The idler stage gear 906, idler gears 905, 903, pinion gear 901, and idler gear 904 are examples of connection parts (intermediate transmission parts) that connect the drum gear 902 and the timing belt 910. The pinion gear 901 is an example of an output transmission member. As shown in Figure 9(a), a drive train is formed including the pinion gear 901, idler gears 903, 905, idler stage gear 906, drum gear 902, drive stabilization unit G5, timing belt 910, and idler gear 904.

[0130] In the configurations of Examples 1 to 5, the drive train included multiple gears, but as in this embodiment, the drive train may also include a timing belt. In this embodiment, the timing belt 910 functioned as the second transmission member, but a timing belt may also be used as the first transmission member or as a connecting part. That is, the drive train may include at least one gear, or at least one timing belt. In this modified configuration as well, the spring force of the torsion coil spring 909 maintains contact between the transmission members in the drive train. The same effects as in each of the above embodiments can be obtained with this modified configuration as well.

[0131] The configurations of each of the above embodiments can be combined with each other. Furthermore, although the drive train in each embodiment was a drive train for driving the photosensitive drum, it can be used as a drive train for various rotating bodies, such as the developing roller, the transport roller for the recording material S, and the drive roller for the transfer belt. Also, for example, the drive train may be configured to drive the photosensitive drum as the first rotating body and the drive roller for the transfer belt as the second rotating body.

[0132] The disclosure of embodiments of the present invention includes the following configurations. (Composition 1) An image forming apparatus, First transmission member and The second transmission member, A third transmission member that rotates in a first rotational direction about a rotation axis, the third transmission member engaging with the first transmission member and separated from the second transmission member, A fourth transmission member that rotates in the first rotational direction about the rotation axis, the fourth transmission member engaging with the second transmission member and being separated from the first transmission member, A biasing member connected to the third transmission member and the fourth transmission member, wherein one of the third transmission member and the fourth transmission member biases in a first rotational direction and the other biases in a second rotational direction opposite to the first rotational direction. A closed-loop drive train is formed including the first transmission member, the second transmission member, the third transmission member, the biasing member, and the fourth transmission member, with a connecting portion connected to the first transmission member and the second transmission member, It has, The rotational speed of the third transmission member is the same as the rotational speed of the fourth transmission member. An image forming apparatus characterized by the following features. (Configuration 2) The image forming apparatus according to configuration 1, characterized in that the third transmission member and the fourth transmission member are arranged coaxially. (Composition 3) The first transmission member has a plurality of first teeth, The second transmission member has a plurality of second teeth, The third transmission member has a plurality of third teeth that mesh with the plurality of first teeth, The image forming apparatus according to configuration 1 or 2, characterized in that the fourth transmission member has a plurality of fourth teeth that mesh with the plurality of second teeth. (Composition 4) The number of teeth of the aforementioned plurality of third teeth and the number of teeth of the aforementioned plurality of fourth teeth are the same. The number of teeth of the plurality of first teeth and the number of teeth of the plurality of second teeth are the same. The image forming apparatus according to configuration 3, characterized in that it is a picture forming apparatus. (Composition 5) The image forming apparatus according to any one of configurations 1 to 4, characterized in that the drive train includes at least one gear. (Composition 6) The image forming apparatus according to any one of configurations 1 to 5, characterized in that the drive train includes at least one timing belt. (Composition 7) The third transmission member includes a first coupling that engages with the first rotating body and transmits driving force to the first rotating body. An image forming apparatus according to any one of configurations 1 to 6, characterized by the above. (Composition 8) The image forming apparatus according to configuration 7, characterized in that the first rotating body is a photosensitive drum. (Composition 9) The image forming apparatus according to configuration 7, characterized in that the first rotating body is a drive roller for rotating the transfer belt. (Composition 10) The fourth transmission member includes a second coupling that engages with the second rotating body and transmits driving force to the second rotating body. The image forming apparatus according to configuration 7, characterized by the features described above. (Composition 11) The first rotating body is a first photosensitive drum, The aforementioned second rotating body is a second photosensitive drum. The image forming apparatus according to configuration 10, characterized in that... (Composition 12) The aforementioned first rotating body is a photosensitive drum, The second rotating body is a drive roller that rotates the transfer belt. The image forming apparatus according to configuration 10, characterized in that... (Composition 13) Further including a power source, The image forming apparatus according to any one of configurations 1 to 12, characterized in that the drive train includes an output transmission member driven by the drive source. (Composition 14) An image forming apparatus according to any one of configurations 1 to 12, characterized in that it includes a release means for releasing the application of a biasing force from the biasing member to at least one of the third transmission member or the fourth transmission member. (Composition 15) The image forming apparatus according to configuration 14, characterized in that the release means is configured to transition from a release state in which the biasing force applied to at least one of the third transmission member or the fourth transmission member is released before image forming is performed, to a biased state in which a biasing force is applied to at least one of the third transmission member or the fourth transmission member. (Composition 16) The image forming apparatus according to configuration 15, characterized in that the release means is configured to return to the release state after image forming has been performed. [Explanation of symbols]

[0133] 2K, 2C, 2M, 2Y…Photosensitive drum, G…Drive stabilization unit, 200…Motor, 201(Y, M, C, K)…Drum gear, 202(C, K)…Idler stage gear, 203…Attachment gear, 204…First adjustment gear, 205…Second adjustment gear, 206…Torsion coil spring, 207…Pinion gear

Claims

1. An image forming apparatus, First transmission member and The second transmission member and A third transmission member that rotates in a first rotational direction around a rotation axis, the third transmission member engaging with the first transmission member and separated from the second transmission member, A fourth transmission member that rotates in the first rotational direction about the rotation axis, the fourth transmission member engaging with the second transmission member and being separated from the first transmission member, A biasing member connected to the third transmission member and the fourth transmission member, wherein one of the third transmission member and the fourth transmission member biases in a first rotational direction and the other biases in a second rotational direction opposite to the first rotational direction. A closed-loop drive train is formed including the first transmission member, the second transmission member, the third transmission member, the biasing member, and the fourth transmission member, with a connecting portion connected to the first transmission member and the second transmission member, It has, The rotational speed of the third transmission member is the same as the rotational speed of the fourth transmission member. An image forming apparatus characterized by the following features.

2. The image forming apparatus according to claim 1, characterized in that the third transmission member and the fourth transmission member are arranged coaxially.

3. The first transmission member has a plurality of first teeth, The second transmission member has a plurality of second teeth, The third transmission member has a plurality of third teeth that mesh with the plurality of first teeth, The image forming apparatus according to claim 1, characterized in that the fourth transmission member has a plurality of fourth teeth that mesh with the plurality of second teeth.

4. The number of teeth of the plurality of third teeth and the number of teeth of the plurality of fourth teeth are the same. The number of teeth of the plurality of first teeth and the number of teeth of the plurality of second teeth are the same. The image forming apparatus according to feature 3.

5. The image forming apparatus according to claim 1, characterized in that the drive train includes at least one gear.

6. The image forming apparatus according to claim 1, characterized in that the drive train includes at least one timing belt.

7. The third transmission member includes a first coupling that engages with the first rotating body and transmits driving force to the first rotating body. The image forming apparatus according to feature 1.

8. The image forming apparatus according to claim 7, characterized in that the first rotating body is a photosensitive drum.

9. The image forming apparatus according to claim 7, characterized in that the first rotating body is a drive roller for rotating the transfer belt.

10. The fourth transmission member includes a second coupling that engages with the second rotating body and transmits driving force to the second rotating body. The image forming apparatus according to feature 7.

11. The first rotating body is a first photosensitive drum, The aforementioned second rotating body is a second photosensitive drum. The image forming apparatus according to feature 10.

12. The first rotating body is a photosensitive drum, The aforementioned second rotating body is a drive roller that rotates the transfer belt. The image forming apparatus according to feature 10.

13. Further including a power source, The image forming apparatus according to any one of claims 1 to 12, characterized in that the drive train includes an output transmission member driven by the drive source.

14. The image forming apparatus according to any one of claims 1 to 12, characterized in that it includes a release means for releasing the application of a biasing force from the biasing member to at least one of the third transmission member or the fourth transmission member.

15. The image forming apparatus according to claim 14, characterized in that the release means is configured to transition from a release state in which the biasing force applied to at least one of the third transmission member or the fourth transmission member is released before image forming is performed, to a biased state in which a biasing force is applied to at least one of the third transmission member or the fourth transmission member.

16. The image forming apparatus according to claim 15, characterized in that the release means is configured to return to the release state after image formation has been performed.

Images